Antibiotic–Heparin Lock: In Vitro Confirmation of Antibacterial Activity

Objective: To determine whether high concentrations of antibiotic “locked” into a central venous catheter with heparin would retain sufficient antimicrobial activity to inhibit the growth of organisms commonly causing catheter-related infections in patients undergoing hemodialysis. Methods: Cefazolin, vancomycin, ceftazidime (all at final concentrations of 10 mg/mL), and gentamicin (final concentration 5 mg/mL) were “locked” separately with heparin sodium (final concentration 5000 IU/mL) in central venous catheters. The catheters were incubated for 72 h at 37°C in a dark incubator. The solutions were then drained from the catheters and used for microbiological testing against organisms commonly causing catheter-related infections. Results: In all cases, the antibiotic–heparin solutions drained from central venous catheters after 72 h at 37°C produced zones of inhibition that were not different from those produced by antibiotic controls (at 5 mg/mL). Conclusions: Each of cefazolin, vancomycin, ceftazidime, and gentamicin locked into central venous catheters with heparin sodium had the ability to inhibit the growth of microorganisms commonly causing catheter-related infections and should be suitable for use in an antibiotic–heparin lock for further in vitro and prospective clinical trials.